linux-kernel - Re: [PATCH v1 03/24] arm64: Move MAIR_EL1

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Message-ID: <d28d29b91804d97a643bd02c5d1cec95@kernel.org>
Date:   Tue, 10 Nov 2020 14:49:35 +0000
From:   Marc Zyngier <maz@...nel.org>
To:     David Brazdil <dbrazdil@...gle.com>
Cc:     kvmarm@...ts.cs.columbia.edu, linux-arm-kernel@...ts.infradead.org,
        linux-kernel@...r.kernel.org, James Morse <james.morse@....com>,
        Julien Thierry <julien.thierry.kdev@...il.com>,
        Suzuki K Poulose <suzuki.poulose@....com>,
        Catalin Marinas <catalin.marinas@....com>,
        Will Deacon <will@...nel.org>, Dennis Zhou <dennis@...nel.org>,
        Tejun Heo <tj@...nel.org>, Christoph Lameter <cl@...ux.com>,
        Mark Rutland <mark.rutland@....com>,
        Lorenzo Pieralisi <lorenzo.pieralisi@....com>,
        Quentin Perret <qperret@...gle.com>,
        Andrew Scull <ascull@...gle.com>,
        Andrew Walbran <qwandor@...gle.com>, kernel-team@...roid.com
Subject: Re: [PATCH v1 03/24] arm64: Move MAIR_EL1_SET to asm/memory.h

On 2020-11-09 11:32, David Brazdil wrote:
> KVM currently initializes MAIR_EL2 to the value of MAIR_EL1. In
> preparation for initializing MAIR_EL2 before MAIR_EL1, move the 
> constant
> into a shared header file.
> 
> Signed-off-by: David Brazdil <dbrazdil@...gle.com>
> ---
>  arch/arm64/include/asm/memory.h | 13 +++++++++++++
>  arch/arm64/mm/proc.S            | 13 -------------
>  2 files changed, 13 insertions(+), 13 deletions(-)
> 
> diff --git a/arch/arm64/include/asm/memory.h 
> b/arch/arm64/include/asm/memory.h
> index cd61239bae8c..aca00737e771 100644
> --- a/arch/arm64/include/asm/memory.h
> +++ b/arch/arm64/include/asm/memory.h
> @@ -152,6 +152,19 @@
>  #define MT_S2_FWB_NORMAL	6
>  #define MT_S2_FWB_DEVICE_nGnRE	1
> 
> +/*
> + * Default MAIR_EL1. MT_NORMAL_TAGGED is initially mapped as Normal 
> memory and
> + * changed during __cpu_setup to Normal Tagged if the system supports 
> MTE.
> + */
> +#define MAIR_EL1_SET							\

If we are going to use this at EL2 directly, consider renaming it to
MAIR_ELx_SET, as we do for other constants that are shared across 
exception
levels.

> +	(MAIR_ATTRIDX(MAIR_ATTR_DEVICE_nGnRnE, MT_DEVICE_nGnRnE) |	\

This creates an implicit dependency between sysreg.h and memory.h.
Consider including asm/sysreg.h, assuming this doesn't create any 
circular
dependency, or even move it to sysreg.h altogether.

> +	 MAIR_ATTRIDX(MAIR_ATTR_DEVICE_nGnRE, MT_DEVICE_nGnRE) |	\
> +	 MAIR_ATTRIDX(MAIR_ATTR_DEVICE_GRE, MT_DEVICE_GRE) |		\
> +	 MAIR_ATTRIDX(MAIR_ATTR_NORMAL_NC, MT_NORMAL_NC) |		\
> +	 MAIR_ATTRIDX(MAIR_ATTR_NORMAL, MT_NORMAL) |			\
> +	 MAIR_ATTRIDX(MAIR_ATTR_NORMAL_WT, MT_NORMAL_WT) |		\
> +	 MAIR_ATTRIDX(MAIR_ATTR_NORMAL, MT_NORMAL_TAGGED))
> +
>  #ifdef CONFIG_ARM64_4K_PAGES
>  #define IOREMAP_MAX_ORDER	(PUD_SHIFT)
>  #else
> diff --git a/arch/arm64/mm/proc.S b/arch/arm64/mm/proc.S
> index 23c326a06b2d..25ff21b3a1c6 100644
> --- a/arch/arm64/mm/proc.S
> +++ b/arch/arm64/mm/proc.S
> @@ -45,19 +45,6 @@
>  #define TCR_KASAN_FLAGS 0
>  #endif
> 
> -/*
> - * Default MAIR_EL1. MT_NORMAL_TAGGED is initially mapped as Normal 
> memory and
> - * changed during __cpu_setup to Normal Tagged if the system supports 
> MTE.
> - */
> -#define MAIR_EL1_SET							\
> -	(MAIR_ATTRIDX(MAIR_ATTR_DEVICE_nGnRnE, MT_DEVICE_nGnRnE) |	\
> -	 MAIR_ATTRIDX(MAIR_ATTR_DEVICE_nGnRE, MT_DEVICE_nGnRE) |	\
> -	 MAIR_ATTRIDX(MAIR_ATTR_DEVICE_GRE, MT_DEVICE_GRE) |		\
> -	 MAIR_ATTRIDX(MAIR_ATTR_NORMAL_NC, MT_NORMAL_NC) |		\
> -	 MAIR_ATTRIDX(MAIR_ATTR_NORMAL, MT_NORMAL) |			\
> -	 MAIR_ATTRIDX(MAIR_ATTR_NORMAL_WT, MT_NORMAL_WT) |		\
> -	 MAIR_ATTRIDX(MAIR_ATTR_NORMAL, MT_NORMAL_TAGGED))
> -
>  #ifdef CONFIG_CPU_PM
>  /**
>   * cpu_do_suspend - save CPU registers context

Thanks,

         M.
-- 
Jazz is not dead. It just smells funny...